What is the amount of light that passes through the lens and reaches the digital sensor called?

The amount of light that passes through the lens and reaches the digital sensor is called exposure.
So, exposure determines how much light or darkness will get to the sensor, and thus how light or dark the image will be when you take a photo. There are settings that are responsible for this: ISO, aperture, and shutter speed - which together are called "the exposure triangle."

Analysis of da vinci's vitruvian man. another of da vinci's most famous works is that of the vitruvian man, created around 1490. the official title of the drawing is “le proporzioni del corpo umano secondo vitruvio,” or “the proportions of the human body according to vitruvius.”